the importance of spelling

About a year ago we were studying various infectious diseases. My professor's powerpoint kept mentioning the various dangers of "plaque" and I for the life of me couldn't figure out what was so important or dangerous!

For heaven's sakes, are we in Dental School here?! Plaque is important, but sheesh, these people are obsessed about their teeth!

Shouldn't teeth fit into the gastrointestinal system somehow, and not infectious diseases?

How can plaque kill you?! That seems a bit far-fetched to me! That would have to be some pretty extensive plaque!

Oh....I think she means plague.